Cockpit Recorder Holds Few Clues to Pilot Actions

An outdated cockpit voice recorder with only a 30-minute capacity may stymie federal investigators' effort to determine why pilots of a Northwest Airlines jet failed to respond to air-traffic controllers for more than an hour and overshot their scheduled stop by 150 miles, according to government and industry investigators.

The crew of Northwest Flight 188, en route to Minneapolis from San Diego Wednesday evening with 144 passengers aboard, maintained radio silence for a total of 78 minutes and flew past their destination without descending or slowing down. The Airbus A320's bizarre odyssey -- which violated basic cockpit discipline and traffic-control procedures -- also has prompted investigators to question whether the pilots might have been asleep at the controls.

The pilots told law-enforcement officials who interviewed them upon landing that they had been engaged in a heated discussion about company matters and "lost situational awareness." They subsequently recounted the same explanation to fellow pilots, according to investigators.

Neither Northwest's parent, Delta Air Lines Inc., nor government investigators have identified the pilots. But an airport police report released Friday identifies them as Timothy B. Cheney, the captain, and Richard I. Cole, the first officer, and indicates they both passed preliminary breathalyzer tests.

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The National Transportation Safety Board displays the cockpit voice and flight data recorders from the October 21 Northwest Airlines Flight 188, at NTSB headquarters on Friday in Washington.
Getty Images

The Flight 188 probe is only in its initial stages. But already there appears to be increasing friction between the National Transportation Safety Board, which investigates aircraft safety lapses, and the Federal Aviation Administration, which regulates airlines and pilots. Before the NTSB's investigation revs up, FAA officials have sent letters warning the pilots that they could lose their licenses.

No mechanical or other equipment problems were reported to controllers. But as investigators retrieve data from the cockpit recorder, they likely will be hard-pressed to determine whether pilot fatigue or distraction was the primary cause of the incident.

Once the cockpit crew resumed communication with controllers on the ground, the jet circled back toward Minneapolis and flew for roughly another half hour before landing safely without any injuries.

ENLARGE

According to investigators, that means the cockpit recorder is likely to have captured only the tail end of the flight, when the pilots already were back in contact with the ground. The recorder erases old conversations and records over them in a continuous loop. Newer versions of the device capture conversations and cockpit sounds for as long as two hours.

In an interview with ABC News Friday, co-pilot Cole said "I can assure you none of us was asleep," the Associated Press reported. He declined further comment except to say, "I am not doing very good."

As the probe accelerates, safety-board investigators will interview both pilots and their supervisors. The board's staff will research the pilots' work and rest histories during the few days preceding the flight, and examine the flight-data recorder -- which has a two-hour capacity -- for other possible clues. To get a better perspective on the work habits and flying skills of the pilots, safety-board experts will interview fellow aviators.

Cockpit Recorders

Which aircraft have them: All large commercial aircraft and some smaller commercial and private aircraft are required to carry cockpit voice recorders.

Microphone location: The microphone is usually placed in the overhead instrument panel between the two pilots.

Length of recording: Older models, like the one aboard Flight 188, have a 30-minute memory. On newer models, the length has been extended.

What is released: A committee reviews the recording and creates a written transcript that includes the time sequence of sounds and communications.

Pilots typically engage autopilots after takeoff, rely on flight-management computers to navigate and adjust speeds while cruising, then program in descent trajectories to approach runways.

During a three-hours-plus trip such as the one flown by Northwest Flight 188, pilots essentially monitor instruments in a darkened cockpit surrounded by rhythmic engine noises. Research has demonstrated that under those conditions, pilots can doze off without realizing it.

Safety experts and investigators initially suspected that both pilots, who apparently engaged the autopilot while cruising routinely at 37,000 feet, may have nodded off. But the pilots said they simply lost track of their position after they became distracted amid their conversation.

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That accounting has been questioned by many air-safety experts, who say regular contact with traffic control is second nature for commercial pilots. Moreover, these experts said, there should have been ample visual cues and even aural warnings in the cockpit to alert the pilots to their situation and the need to contact controllers or company dispatchers.

Given the nationwide network of radar and traffic-control facilities, "it's almost unthinkable in the U.S." for a commercial aircraft to be out of touch with controllers for such a lengthy period, former FAA chief crash investigator Steve Wallace told CNN Friday.

Delta said it suspended the two pilots from flying duties, launched its own investigation and is cooperating with efforts by the NTSB and FAA to get to the bottom of what happened.

Late Friday, the FAA said it "sent letters of investigation to the two pilots" involved in the incident. "Depending on the outcome of our investigation," the FAA said, "this action could lead to emergency suspension or revocation" of their licenses.

Since there was no accident or injuries, the FAA believes it should take the lead, according to one industry official familiar with the matter. The safety board, on the other hand, wants to retain authority over all significant airliner incidents.

Wednesday's incident, as embarrassing and jarring as it may be for the airline and passengers, nonetheless could spark further refinements in cockpit technology to help prevent pilots from nodding out. Some Boeing aircraft, for example, have systems that set off a buzzer if pilots fail to adjust certain controls, transmit over the radio or otherwise signal to onboard computers that they are awake.

According to pilots familiar with Airbus aircraft, the jet that overflew Minneapolis is designed to provide only visual warnings.

Despite the abbreviated voice recording, investigators hope they still will be able to analyze some after-the-fact cockpit discussions that might shed light on the sequence of events. One person familiar with the issue said the digital cockpit voice recorder is in good shape and safety board experts believe they will be able to recover the full 30-minutes of data. The safety board expects to interview the pilots next week. As of Friday, it wasn't clear whether Delta safety officials had conducted a formal, detailed interview with the pilots

The incident comes as the FAA plans a wholesale rewrite of regulations addressing pilot fatigue. One change being considered is whether pilots should be allowed to take brief naps during certain portions of some flights. Research has shown that short naps midflight could help make pilots more alert during landings. While currently strictly forbidden in the US, such "controlled napping" is endorsed under particular conditions by some foreign carriers.

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